In general the present paper is, in addition to the papers by S. Boatto and J. Koiller already mentioned,
much in spirit of papers [1]}, [2]}, [3]}, [4]}, [5]}
by S. G. Llewellyn Smith, R. J. Nagem, C. Grotta Ragazzo, H. Viglioni, and Q. Wang.
The paper [6]} by A. Bogatskiy
contains ideas concerning the higher genus case which are somewhat similar to those in the present paper,
see in particular Section A.3 in [6]}.
We wish to mention also the work [8]} by A. V. Borisov and I. S. Mamaev, and the very early article
[9]} (cited in [8]}, [2]}) by A. A. Fridman and
P. Ya. Polubarinova. That work, from 1928, may be one of the first papers on motion of dipoles and other higher singularities.
Fridman was a famous cosmologist and Pelageya Yakolevna Polubarinova (or Polubarinova-Kochina, after marriage) was a young
(at that time) disciple of Fridman. This remarkable woman wrote her first paper in 1924, and was scientifically active
throughout her life. Her published papers and books span a period of 75 years, the last paper appearing the same
year as she died, one hundred years of age. See [12]} for a short biography related to her work on Hele-Shaw flows.
